基于二元介质模型的砂类土小应变剪切模量评价方法  

A new method for evaluating small-strain shear modulus of sandy soils based on binary medium model

作　　者：吴琪[1] 刘抗 郭启洲 赵凯[1] 陈国兴[1] WU Qi;LIU Kang;GUO Qi-zhou;ZHAO Kai;CHEN Guo-xing(Institute of Geotechnical Engineering,Nanjing Tech University,Nanjing,Jiangshu 210009,China;Civil Engineering department,Xi'an Jiaotong-Liverpool University,Suzhou,Jiangshu 215123,China)

机构地区：[1]南京工业大学岩土工程研究所,江苏南京210009 [2]西交利物浦大学土木工程学院,江苏苏州215123

出　　处：《岩土力学》2020年第11期3641-3650,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.52008206,No.51978335,No.52008206);国家重点发展计划项目(No.2018YFC1504301-03)。

摘　　要：为探讨初始有效围压σ’c0、孔隙比e及细粒含量FC对饱和砂类土小应变剪切模量Gmax的影响,对具有不同物理特性的3类饱和砂类土进行了一系列均等固结弯曲元试验,结果表明:表征σ’c0。对Gmax影响程度的应力指数n为与土类相关的常数,且n与砂类土复合级配特性参数CusCuf有较好的指数相关性(Cus、Cuf分别为纯砂粒、纯细粒的不均匀系数)。Hardin模型拟合参数A随FC的增大而减小,且两者呈现指数相关性:但拟合参数d与FC没有明显的单一相关性。结合文献中3类砂类土的Gmax试验数据分析表明:各砂类土的应力修正小应变剪切模量Gmax/(σ’c0/Pa)n(Pa为标准大气压)随其等效骨架孔隙比esk*的增大而单调地降低,且两者呈现较好的幂函数关系,基于二元介质模型建立的广义Hardin模型可以合理评价具有不同σ’c0、FC以及e的各类砂类土的Gmax。To investigate the effect of initial effective consolidation stress σ’c0,void ratio e,and fines content FC on the small-strain shear modulus Gmax of saturated sandy soils,a series of isotropically consolidated bender element tests is performed on three saturated sandy soils with various physical properties.The test results show that the stress exponent n,reflecting the rate of Gmaxincrement due to the enhancement of σ’c0,presents a soil-specific constant,and there is a good exponential correlation between n and the synthesizing grain size distribution parameter Cus·Cuf of sandy soils.Fitting parameter A of Hardin model decreases as FC increases,and an exponential correlation is found.But there is no obvious single correlation between fitted parameter d and FC.Combined with the test data of Gmax of three saturated sandy soils in the literature,it is found that the stress-corrected small-strain shear modulus Gmax/σ’c0/Pa)n for different types of sandy soils decreases monotonically with the increase of the equivalent skeleton void ratio esk*,and a good power relationship between Gmax/(σ’c0/Pa)n and esk* is then obtained.Generalized Hardin model that allows unified characterization of Gmax values for different types of sandy soils with various σ’c0,e and FC is established based on binary medium model.

关 键 词：饱和砂类土 小应变剪切模量 应力指数 等效骨架孔隙比 广义Hardin模型 

分 类 号：TU521[建筑科学—建筑技术科学]